Monday
April 21, 2014

Posts by jin


Total # Posts: 126

chemistry
if a college student went into the lab and produced 45 grams of Na2CO3, what is percent yield of this trial?

chemistry
LAST QUESTION: When solid NH4NO3 decomposes, a mixture of gases is obtained: 2 NH4NO3(s)--> 4H2O(g) + O2(g) + 2 N2(g) In an experiment, 5.02 g NH4NO3 decomposes completely in a rigid 5.00-L container. What is the total pressure in the container if the final temperature is 2...

chemistry
It takes 19.6 mins for a 10.0mL sample of an unknown gas to effuse through a pinhole. A 10.0mL sample of He, required 5.05mins. What is the molar mass of the unknown gas? I got that you have to do : effuse rate of He/Effuse rate of Mx = Square root of (Mx/MHe) but then im stuc...

chemistry
Carbon monoxide, CO and hydrogen, H2, react accordingly: 4CO(g)+9H2(g)-->C4H10(g)+4H2O What volume of the EXCESS REACTANT remains if 17.2L CO and 42.1L H2 are allowed to react? Assume both gases are measured at 711 degree celsius and 1.33atm.

chemistry
What is the density of CH4 gas at 32.7 degree celsius and 109kPa? The molar mass of CH4 is 16.042g/mol.

English on different cultures
Because the stories are often well done, or people look to get some eye-candy; or even just look at all the productions their favorite "idol" or "actors" are in. :)

algebra
A ball is thrown into the air with an upward velocity of 28 ft/s. Its height (h) in feet after t seconds is given by the function h = –16t² + 28t + 7. How long does it take the ball to reach its maximum height? What is the ball’s maximum height? How do I solve t...

History
Describe and evaluate President Eisenhower’s policy regarding Joseph McCarthy.

I don't know what to do?
Y < 4x so when x = 1 then y <4 when x = 2 then y <8 when x = 3 then y < 12 ....

chemistry
lithium + gold(III) chloride +lithium chloride + gold need to balance equation

Calculus
find all values of x for which function is differentiable. y=lnx^2 why is the answer= for all x doesn't equal 0?

math
5/2 because 60 divided by 12 = 5 24 divided by 12 = 2

Calculus
find the derivative y= csc^-1 (secx) 0 less than or equal to x less than or equal to 2¤Ð what did i do wrong? - 1/ secx sqrt(secx^2 -1) * secxtanx

9 th science
distinguish between tolerance range and optimal range

calculus
f(x)=8x^3+1x^2–8x+2/–7x^2–4x+9 Find the equation of the non-vertical asymptote. y = Does f(x) intersect its non-vertical asymptote? (yes or no) What is the smallest value of x at which f(x) intersects its non-vertical asymptote? ( Enter No in the question blank...

calculus
Consider the function f(x)=–3x3–1x2+1x+1Find the average slope of this function on the interval (–2–1). By the Mean Value Theorem, we know there exists a c in the open interval (–2–1) such that f(c) is equal to this mean slope. Find the value of c...

calculus
se differential, i.e., linear approximation, to approximate (8.4)^(1/3) as follows: Let f(x)=(x )^(1/3). The linear approximation to f(x) at x=8 can be written in the form y=mx+b where m is: and where b is: Using this, we find our approximation for (8.4)^(1/3) is

calculus
The circumference of a sphere was measured to be 78.000 cm with a possible error of 0.50000 cm. Use linear approximation to estimate the maximum error in the calculated surface area. Estimate the relative error in the calculated surface area.

calculus
A street light is at the top of a 16 ft tall pole. A woman 6 ft tall walks away from the pole with a speed of 4 ft/sec along a straight path. How fast is the tip of her shadow moving when she is 40 ft from the base of the pole?

math
The horizontal asymptotes of the curve y=12x/(x4+1)^(1/4)

math
he circumference of a sphere was measured to be 78000 cm with a possible error of 050000 cm. Use linear approximation to estimate the maximum error in the calculated surface area.

math
A spherical snowball is melting in such a way that its diameter is decreasing at rate of 0.2 cm/min. At what rate is the volume of the snowball decreasing when the diameter is 12 cm. (Note the answer is a positive number).

math
for dB/dt, i got -295 is that correct? so i just plug it in to find dH/dt?

math
what is the derivative of f(x)=6sin2x I put 12cosx...

math
How do you find the derivative of square root of five /t^5? how do you find the derivative of square root of five /t^5 I know that f=a t^-n f'= -an t^(-n-1) and i tried putting -25/{[2sqrt(5/t^5)]/(t^4)}

math
If a ball is thrown vertically upward from the roof of 32 foot building with a velocity of 80 ft/sec, its height after t seconds is s(t)=32+80t–16t2. What is the maximum height the ball reaches? What is the velocity of the ball when it hits the ground (height 0)? for max...

math
If f(x)=(x^2+3x+4)^2 how do you find the derivative I tried doing 2 (2x+3)..

math
i already know this rule but im still having trouble solving it

math
how do you find the derivative of square root of 5 /t^5

math
how do you find sin7x/4x when lim x goes to 0 the answer is 7/4

math
how does secx(tanx + tan^2x- sec^2x) simplified to sec x (tanx -1)?

math
how do you find the derivative of square root of x

math
I don't know how y-1=-1/3(x-3) is simplifes to x+3y-6=0

math
how do you find the equation of a line knowing (-5,-5) and (-2.-3) so the slope will be 2/3...

math
i meant what happens as v goes to c-

math
In the theory of relativity, the mass of a particle with velocity v is m=mo/(square root ((1- v^ 2)/ c^2)) where mo is the mass of the particle at rest and ci s the speed of light. What happens as v goes to c?

math
how do you factor our a cube? x^3 +8

math
evaluate the limit as lim h goes to 0 ((2+h)^3 - 8)/h the answer is twelve but I don't know how to factor out the cube

math
evaluate the limit as lim goes to -1 (x^2 +2x +1)/ (x^4 -1) the answer is zero but i don't know how to get it

math
i got -2 but i don't know what the theorem is called

math
as lim goes to 4

math
if f(x)is greater or equal to 10x–42 but less than or equal to x2+2x–26 determine limx4f(x) = What theorem did you use to arrive at your answer?

math
If a ball is thrown straight up into the air with an initial velocity of 95 ft/s, it height in feet after t second is given by y=95t–16t2. Find the average velocity for the time period begining when t=1 and lasting (i) 01 seconds: (ii) 001 seconds: (iii) 0001 seconds: Fi...

math
if f(x)is greater or equal to 10x–42 but less than or equal to x2+2x–26 determine limx4f(x) = What theorem did you use to arrive at your answer?

math
An open box is to be made from a flat piece of material 18 inches long and 2 inches wide by cutting equal squares of length xfrom the corners and folding up the sides. Write the volume Vof the box as a function of x. Leave it as a product of factors, do not multiply out the fa...

calculus
how do you properly write the answer?

calculus
find the domain of function f(x)= (5x + 4)/(x^2 + 3x + 2) is the answer.. x can't be -2 or -1?

chemistry
Rates of chemical reactions usually depend on temperature and pressure. However, half-life of all radioactive elements is independent of both T and p. How can these decay rates be independent of T if we beleive in the Arrhenius equation?

chemistry
how do you solve this? The candy indistry converts sucrose (C11H22O11,table sugar),a crystalline material, to invert sugar, a hydrolzyed [rpdict tjat os 50:50 frutose and glucose. The hydrolysis occurs in water, quite slowly, at an elevated temperature of 55¨¬C. The re...

chemistry
Which of the following salts would show an appreciable pH-dependent solubility? a. AgCl b. Mg(OH)2 c. BaF d. both b and c e. all of the above I put c as my answer (not sure if its right, but can you explain how you would solve this)

chemistry
A salt that could decrease the ionization of HCOl in soln is probably a. NaOH b. NaCl c. NaOCl d. NaH e. none of these how would you solve this

chemistry
In titration of a 0.10M soln of Na2Co3 with HCL which of the following will be present in the largest concentration at the first equivalence point? a. Co3^2- b. HCO3- c. H+ d. H2CO3 e. OH-

chemistry
Which of the following when added to 100.0mL of a 0.100M soln of NH4Cl would produce a buffer soln? a.100.0mL of 0.100 M HCl soln b. 100.0mL of 0.050M NaOH soln c. 100.0mL of 0.100M NaOH soln d. 100.0mL of 0.050M NH4No3 soln e.none of the above

chemistry
why is it that [H2O] is NOT included in the rate law, even though it is a reactant?

chemistry
why is it that [H2O] is NOT included in the rate law, even though it is a reactant?

chemistry
Faraday¡¯s Law of Electrolysis • Practice Problem. • What is the oxidation state of the osmium atom in an unknown salt if 26.7 grams of osmium plate out when a current of 15 amps is passed through a solution of this salt for 1 hour?

chemistry
To have a color, the transition metal complex should have an electron in a d-orbital, and an unoccupied spot in a higher energy d-orbital. • Practice Problem. • Predict whether each of the following complexes could be colored: (a) [Sc(H2O)6]3+ (b) [Ti(H2O)6]3+ (c) ...

chemistry
Determine the oxidation state of each transition metal in the following cmpds. (a) Na2MoO4 (b) KAuCl4 (c) MgWO4 and (d) Ni(CO)4

chemistry
How do you know if these solutions are acidic, basic, or nearly neutral? a. NH4NO2 b. Cr(NO3)3

chemistry
The values of Ksp for AgBr and AgCl, are 7.7x10^-13 and 1.6 x 10^-10. A solution containing a mixture of 2.0x10^-2 M Br and 2.0 x 10^-2M Cl is a candidate for separating using selective precipitation. Solid AgNO3 is added, with a miniature spatula, and without changing the vol...

chem
7.50gram quantity of a diprotic acid was dissolved in water and made up to exactly 250ml. If 25ml of this solution were neutralized by 11.1 mL of 1.0 M KOH then what is the molar mass of the acid? I did 7.50/5.55x10^-3

chemistry
I had this on a test, not sure how to do it Explain, using balanced chemical reactions with the smallest integer coefficients, why each of following occurs. a. CuI2 (insoluble in pure water) dissolves readily in aqueous ammonia, HN3(aq) b. AgBr (insoluble in pure water) dissol...

chemistry
Discuss the spontaneity of an electrochemical reaction in terms of its standard emf (E¨¬cell)

chemistry
Explain, with balanced ionic equations, why a. CuI2 dissolves in ammonia solution b. AgBr dissolves in NaCN solution, c. HgCl2 dissolves in KCL solution.

chemistry
Solid NaI is slowly added to a soln that is 0.010M in Cu+ and 0.010M in Ag+. a. Which compound will begin to precipitate first? b. Calculate [Ag+] when CuI just begins to precipitate/ c. What percent of Ag+ remains in solution at this point?

chemistry
nvm i got the answers

chemistry
Write balanced equations and solubility product expressions for the solubility equlibria of the following compounds: a. CuBr b. ZnC2O4 c. Ag2CrO4 d. Hg2Cl2 e. AuCl3 f. Mn3(po4)2 can you give me some examples using the compounds given?

chemistry
The amount of indicator used in an acid-base titration must be small. why??

chemistry
How do you solve this problem? In a certain industrial process involving a heterogeneous catalyst, the volume of the catalyst (in the shape of a shpere) is 10.0cm^3. Calculate hte surface area of the catalyst. IF the sphere is broken down into eight spheres, each having a volu...

chemistry
the chapter is about chemical kinetics Reaction mechanisms: What does it mean by mechanism of a reaction? What is an elementary step? what is the molecularity of a reaction?

chemistry
how do you solve this problem? consider the reaction A->B the rate of the reaction is 1.6 x 10^-2 M/s when the concentration of A is 0.35 M. Calculate the rate constant if the reaction is a) first order in A and b) second order in A.

chemistry
Determine the overall orders of the reactions to which the following rate laws apply: a) rate= k[NO2]^2 b) rate = k c) k [H2][Br2]^1/2 d) k [NO]^2[O2] is it.. a. 2 b. 0 c. 1 1/2 d. 3

chemistry
how do you solve this What is the pH of the solution created by combining 2.60 mL of the 0.10 M NaOH(aq) with 8.00 mL of the 0.10 M HCl(aq)? with 8.00 mL of the 0.10 M HC2H3O2(aq)? mL NaOH 2.60 pH wHCl: _ pH wHC2H3O2 : _ Complete the table below: What are the pH values if you ...

chemistry
how do you solve this? What is the pH of the solution created by combining 12.30 mL of the 0.10 M NaOH(aq) with 8.00 mL of the 0.10 M HCl(aq)? with 8.00 mL of the 0.10 M HC2H3O2(aq)? mL NaOH pH wHCl pH wHC2H3O2 12.30 Complete the table below: What are the pH values if you take...

chemistry
Which reactants in the reactions below are acting as Br©ªnsted-Lowry bases? NH4 +(aq) + OH−(aq) <-> NH3(aq) + H2O(l) H2PO4 −(aq) + H2O(l) <-> H3O+(aq) + HPO4 2−(aq) is the answer H2O and the H3O+

chemistry
The pKa for hydrochloric acid is −6.0. What is the concentration of HCl(aq) we would expect to find in a 1 M solution of hydrochloric acid? What pH would we expect? how do you solve this problem?

chemistry
The pH of a 0.0642 M solution of a monoprotic acid is 3.86. s this a strong acid? the answer is no, can you explain why??

chemistry
Predict whether the following solutions are acidic, basic, or nearly neutral: a. NaBr, b. K2SO3, c. NH4NO2, d. Cr(NO3). the answer is neutral, basic, acidic, acidic and i am not sure why

chemistry
how do you solve this problem?? What is the original molarity of a solution of formic acid (HCOOH) whose pH is 3.26 at equilibrium? the answer is 2.3 x 10^-3M.

chemistry
how do you solve this problem?? how much NaOH (in grams) is needed to prepare 546mL of solution. What is the pOH of the solution?

chemistry
for SCN- if S-C has a bond order of 1, S=C and C=N have bond orders of 2, and C triple bond N hasa bond order of 3, ... Do the bond length in SCN- point to one resonance structure over the other? Which one?

chemistry
how do you know which bonds have a more pie bonding character than the other bond? and how do you know if it point to one resonance structure over the others?

chemistry
how do you know which resonance structure is more stable according to the energy? does higher energy mean more stable?

chemistry
did you get number 9?!!

chemistry
The Fe(ox)33– complex ion creates an emerald green solution when dissolved. The observed solution color of the complex indicates the size of o is: A. large. B. small. C. in between. D. inconclusive, more information is needed. The observed solution color of the complex i...

PHYSICS
Wile E. Coyote is holding a “HEAVY DUTY ACME ANVIL” on a cliff that is 40.0 meters high. The Roadrunner (beep-beep), who is 1.0 meter tall, is running on a road toward the cliff at a constant velocity of 10.0 m/s. Wile E. Coyote wants to drop the anvil on the Roadrun...

physics
A skier leaves the end of a ramp with a velocity of 25.3 m/s and lands 50.3 m from the base of the ramp. How high is the end of the ramp from the ground?

physics
I figured it out. All you need to do is use Wnet = Wforce + Wspring = Kf - Ki twice. Once for the entire displacement Kf - Ki = 0 and once for half way where Kf - Ki = 2.4. Both times you will have a k(spring constant term) in the equation and if you solve for them and set equ...

physics
In Figure (a), a block of mass m lies on a horizontal frictionless surface and is attached to one end of a horizontal spring (spring constant k) whose other end is fixed. The block is initially at rest at the position where the spring is unstretched (x = 0) when a constant hor...

Accounting
How does discounted cash flow differ from the other valuation methods?

Middle school Engllish
My son recently had an English test where he was marked incorrectly, but I think he was correct. I just need some verification. The question: "The whole neighborhood watched him climb in his old pickup and ______ down our street at full speed." The word to use was th...

Accounting
How does the frequency of interest compounding, regardless of the rate of interest or period of accumulation, affect the future value of any given amount?

science
That makes a lot of sense. Thank you!

science
Thank you so much, DrBob! I appreciate it!

science
Would you expect the dissolved oxygen concentration of water samples taken from a lake at 7 am to be higher or lower than samples takn at 5 pm? I feel like there may be more dissolved oxygen in the sample taken at 7 am because photosynthesis probably took place and oxygen was ...

science
A heterotroph

Science.
What effect does water loss (through heavy perpiration) have on a person's endocrine system?

12 Biology
Noncoding DNA sequences on homologous chromosomes exhibit small nucleotide differences- and introns account for this difference. RFLPs are scattered throughout genomes and it serves as a genetic marker for particular location in the genome. A single change in base-pair could m...

science
Those molecules containing carbon atoms are known as organic compounds. It's a vital part of life - especially when we talking about living organisms. Biological diversity has its molecular basis in carbon's ability to form a huge number of molecules with particular sh...

Biology - oxidative phosphorylation
The hydrogen ions are pumped into the intermembrane space from the mitochondrial matrix. Oxygen captures the electrons in the very last step in the electron transport and adding electrons to that oxygen atom and two hydrogen ions form water. No. ATP synthase transports hydroge...

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